Structure analysis and anti-fatigue activity of a polysaccharide from Lepidium meyenii Walp

A polysaccharide was obtained from Lepidium meyenii Walp by hot water extraction and purification by Millipore (100 kD) and Sephadex G-200. The content of polysaccharide was examined to be 89.9% with phenol-sulfuric acid method. Its average molecular weight was estimated to be 2.213 × 10⁶ Da by High Performance Gel Permeation Chromatography (HPGPC). Monosaccharide analysis showed that the polysaccharide was composed of arabinose, mannose, glucose and galactose with the molar ratio of 2.134: 1: 2.78: 2.82. After Smith degradation, methylation, infrared spectroscopy and NMR, the primary structure of the polysaccharide was identified. The backbone of the polysaccharide was composed of →4)-β-D-Galp-(1→ and →4)-α-D-Galp-(1→, while the branches were comprised of →6)-β-D-Glup-(1→, →5)- β-D-Araf-(1→, →3,6)-α-D-Manp-(1→, →3)-α-D-Galp-(1→, and α-D-Glup-(1→. The anti-fatigue effect of the polysaccharide was evaluated using exhaustive swimming test and biochemical indexes. The results indicated the polysaccharide has anti-fatigue effect.     

Structural characterisation of a water-soluble polysaccharide from tissue-cultured Dendrobium huoshanense C.Z. Tang et S.J. Cheng

A water-soluble polysaccharide TC-DHPA4 with a molecular weight of 8.0 × 10⁵ Da was isolated from tissue-cultured Dendrobium huoshanense by anion exchange and gel permeation chromatography. Monosaccharide analysis revealed that the homogeneous polysaccharide was made up of rhamnose, arabinose, mannose, glucose, galactose and glucuronic acid with a molar ratio of 1.28:1:1.67:4.71:10.43:1.42. The sugar residue sequence analysis based on the GC-MS files and NMR spectra indicated that the backbone of TC-DHPA4 consisted of the repeated units:→6)-β-Galp-(1→6)-β-Galp-(1→4)-β-GlcpA-(1→6)-β-Glcp-(1→6)-β-Glcp-(→. The sugar residue sequences β-Glcp-(1→)-α-Rhap-(1→3)-β-Galp-(1→, β-Glcp-(1→4)-α-Rhap-(1→3)-β-Galp-(1→, β-Galp-(1→6)-β-Manp-(1→3)-β-Galp-(1→, and α-l-Araf-(1→2)-β-Manp-(1→3)-β-Galp-(1→ were identified as the branches attached to the C-3 position of (1→6)-linked galactose in the backbone.     

A general method for the synthesis of oligosaccharides consisting of α-(1→2)- and α-(1→3)-linked rhamnan backbones and GlcNAc side chains

A general method has been developed for the synthesis of oligosaccharides consisting of (1→2)- and (1→3)-linked rhamnans with GlcNAc side chains. As examples, highly effective and convergent syntheses of two decasaccharides in the O polysaccharide moiety of the lipopolysaccharide of the phytopathogenic bacterium Pseudomonas syringae pv. ribicola NCPPB 1010 were achieved. The two decasaccharides consist of O polysaccharide repeating units I+II and II+I, respectively. Allyl 3-O-acetyl-4-O-benzoyl-α-l-rhamnopyranoside, allyl 2-O-benzoyl-3-O-chloroacetyl-α-l-rhamnopyranoside, 2,4-di-O-benzoyl-3-O-chloroacetyl-α-l-rhamnopyranosyl trichloroacetimidate, and 3-O-acetyl-2,4-di-O-benzoyl-α-l-rhamnopyranosyl trichloroacetimidate, which were obtained by highly regioselective 3-O-acylations, were used as the key synthons to obtain the required α-(1→2)- and α-(1→3)-linked rhamnoocta saccharide acceptors with 3³- and 3⁷-free hydroxyl groups. Therefore, several disaccharides were synthesized, from which tetrasaccharides and hexasaccharides were then synthesized. Coupling of the hexasaccharide donors with the disaccharide acceptors gave the octasaccharide acceptors. Finally, the coupling of 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl trichloroacetimidate with the octasaccharide acceptors, followed by deprotection, afforded the two target decasaccharides. A repeating hexasaccharide unit of the cell wall polysaccharide of β-hemolytic Streptococci Group A was also synthesized in a similar way.     

A new triterpenoid saponin from the roots of Platycodon grandiflorum

A new triterpenoid saponin, 3-O-β-D-glucopyranosyl 16-oxo-platycodigenin 28-O-β-D-apiofuranosyl-(1→3)-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyra-nosyl ester, was isolated from the roots of Platycodon grandiflorum, together with three known saponins, including platycodin D, deapio platycoside E and platycoside E. The structure of the new compound, named 16-oxo-platycodin D, was elucidated on the basis of spectroscopic data.     

Synthesis,photophysical properties and DFT studies of 2-(3-cyano-4-((2-(4,6-dimethyl-5-nitro-1H-pyrazolo[3,4-b]pyridin-3-yl)hydrazono)methyl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile dye

The chromophore 2-(3-cyano-4-((2-(4,6-dimethyl-5-nitro-1H-pyrazolo[3,4-b]pyridin-3-yl) hydrazono)methyl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile (PPHTCF) was synthesized through coupling of diazotized 3-amino-4,6-dimethyl-5-nitropyrazolo[3,4-b]pyridine with 3-cyano-2-(dicyanomethylene)-4,5,5-trimethylfuran (TCF). The absorption solvatochromism behaviour of PPHTCF, in various solvents, presented ΔE_max = +5.40 where the positive sign suggested red shift occurrence, implying that the PPHTCF has more polar lowest excited state than its ground one. While, the PPHTCF fluorescence spectra afforded λ_em, in 575–633 nm range, and was more dependent on the solvent polarity than the absorption λ^max, despite both exhibited red shift by 58 and 42 nm, respectively. To discover the PPHTCF solvatochromism behaviour in term of “Stokes’ shift”, both of Lippert-Mataga and linear solvation-energy relationship (LSER) formulations have been utilized and the outcomes endorsed that the later was better than the former (R² = 0.9728). Finally, TD-DFT simulated absorption and emission spectra in EtOH revealed that λ^max has been resulted mainly from HOMO → LUMO; HOMO-5 → LUMO and HOMO-2 → LUMO transitions, respectively.     

A new triterpenoid saponin from Gleditsia sinensis and its antiproliferative activity

Chemical investigation of the anomalous fruits of Gleditsia sinensis led to the isolation and identification of a new triterpenoid saponin, 3-O-β-D-xylopyranosyl-(1 → 2)-α-L-arabinopyranosyl-(1 → 6)-β-D-glucopyranosyl oleanolic acid 28-O-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyrano--syl-(1 → 4)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 3)-β-D-glucopyranosyl ester (1), along with other nine known compounds (2–10). All the isolates from this species were reported for the first time. The structure of Compound 1 was determined by a detailed analysis using various analytical techniques, including 1D and 2D NMR. In vitro antiproliferative activities of Compound 1 on MCF-7 and Hep-G2 tumor cell lines were evaluated. IC₅₀ values against the two cell lines were 9.5 and 11.6 μM, respectively.     

Two new flavonoid diglycosides from Cephalotaxus sinensis

Two new acetylated flavonoid diglycosides, scutellarein-5-O-[a-L-rhamnopyranosyl-(1→ 4)-b-D-6-O-acetylglucopyranoside] (1), apigenin-5-O-[a-L-rhamnopyranosyl-(1→2)-b-D-3,6-di-O-acetylglucopyranoside] (2), were isolated from the leaves of Cephalotaxus sinensis. Their structures were determined by chemical and spectroscopic methods including HR-FAB-MS, 1H–1H COSY, HSQC and HMBC experiments.     

Furostanol saponins with inhibitory action against COX-2 production from Tupistra chinensis rhizomes

Two furostanol saponins were obtained from the n-butanol fraction of methanol extract from Tupistra chinensis rhizomes,a folk medicine of Shennongjia Forest District of Hubei Province.Their structures were determined as (25S)-26-O-(β-D-glucopyranosyl)- furost-1β,3β,22α,26-tetrol-3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside (1) and (25R)- 26-O-(β-D-glucopyranosyl)-furost-1β,3β22α,26-tetrol 3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glu- copyranoside (2),on basis of chemical and spectroscopic evidences.1 and 2 displayed marked inhibitory action towards COX-2 production in macrophages of the rat abdomen induced by LPS at 20μg/mL.     

Structural features of an acidic polysaccharide with the potential of promoting osteoblast differentiation from Lycium ruthenicum Murr.

Abstract

The enhanced osteoblast differentiation is beneficial to the prevention of osteoporosis. In this study, a homogeneous polysaccharide (LRP-S2A) with the potential of promoting osteoblast differentiation was obtained from the fruits of Lycium ruthenicum, a traditional herb for treatment of postmenopausal metabolic disorders. Structural identification indicated that LRP-S2A, with a relative molecular weight of 2.65 × 10⁶ Da and an uronic acid content of 41.8%, contained Rha, Ara, Gal, Glc and GlcA in a molar ratio of 1.00 : 2.07 : 0.57 : 2.59 : 4.33 and was composed of a backbone consisting of 6-O-Me-α-(1→4)-D-GlcpA, 2-O-acetyl-α-(1→4)-D-Glcp, α-(1→2,4)-L-Rhap, β-(1→3)-D-Galp andα-(1→3,5)-L-Araf, and some branches consisting of 6-O-Me-α-(1→4)-D-GlcpA and terminal α-L-Araf. These results suggested that LRP-S2A with the potential of promoting osteoblast differentiation was a new acidic polysaccharide.     

Unprecedented N→C[1,4] Boc migration: synthesis of 3-carboxyl functionalized 7-azaindolo[2,1-c][1,4]benzoxazine ring system

Use of 1 equiv excess n-BuLi in synthesis of azaindolo[2,1-c][1,4]benzoxazine heterocycles furnished the corresponding 3-(tert-butyloxycarbonyl) derivatives presumably via an unprecedented intramolecular N→C[1,4] Boc migration. Thus, treatment of N-Boc-2-aminopicoline 1a with 3 equiv of n-BuLi at ?15 °C, to generate the dianion Li₂-1a, followed by the reactions with Weinreb amides 2a–h at ?40 °C, and then allowing the reaction mixture to warm upto rt in a controlled manner (?40 to 0 °C, 2 h; 0 °C to rt, 16 h) led to formation of a series of Boc-group migrated products 7a–h generally in good yield (～70% isolated yield). Surprisingly, going from cyclopentylene to cyclohexylene cases (2d–e to 2g–h), the desired [1,4] Boc migration was found to be a minor fate (yield ～20%). In these instances, N→ortho-C[1,3] Boc-migrated compounds 9g–h (to ortho-aryl position) were obtained as major products. Plausible mechanisms have been invoked for the formation of tetracyclic heterocycle 3a, as well as for the observed N→C[1,4] Boc-group migration phenomena supported by data from anion quenching experiments.     

Size,surface charge and flexibility of vinegar-baked Radix Bupleuri polysaccharide affecting the immune response

Remarkably, nanomaterials can interact with the cells of immune system and either enhance or inhibit its function in many ways. Unfortunately, such valuable information has been overlooked in studies of polysaccharide immune activity. This study isolated a nano-polysaccharide from vinegar-baked Radix Bupleuri by membrane separation system, DEAE-52 and Sephadex-G200. The physicochemical characterization and immunoregulatory activity were studied through DLS, Congo red, Scanning Electron Microscope, UV–Vis, HPGPC, FT-IR, Methylation, NMR, MTT, neutral red and enzyme linked immunosorbent assay. Results showed that VBCP2.5 was an acidic polysaccharide with a molecular weight of 674 kDa. Its monosaccharides composed of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose at a molar ratio of 1.72: 9.59: 57.63: 5.37: 6.71: 18.99. VBCP2.5 possessed micelle forming ability at 52.574 µg/mL and flexible chain conformation, as well as with a small size distribution ～ 84.99 nm and positive charge in stimulated blood fluid and different from that in deionized water. The microtopography was characterized by irregular lamellar, dendritic, cylindrical or spherical aggregates, with folds and cracks on the surface. Structure analyses showed that VBCP2.5 characterized by high proportion of 1,4 linked-α-D-GalpA and a small fraction of RG-I, some other glycosidic linkages included 1,5 linked-α-L-Araf, 1,3,5 linked-α-L-Araf, 1,3,4 linked-Galp, 1,4,6 linked-Manp, t-α-L-Araf, t-β-D-Glcp and t-α-D-Galp were also comprised. VBCP2.5 exhibited immunomodulatory potential which included the promotion of phagocytosis, the release of NO and the secretion of TNF-α and IL-6 of RAW264.7 cells. The possible activation of macrophages by VBCP2.5 may be mediated through endocytosis pathway. Small size, positive charge, shape and flexible conformation may accelerate this process. The information gathered here could lead to new platform for comprehensive understand included primary structure, properties of nanoscale, and correlation with immunoregulation of polysaccharides.     

3-Oxyanthranilic acid derivatives from Actinomadura sp. BCC27169

Eight new compounds including 9′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy) phenyl]nonanoic acid (1), 9′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl] nonanoic acid (2), 11′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy)phenyl]undecanoic acid (3), 11′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl]undecanoic acid (4), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (5), 8-(4′-O-methyl-α-ribopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (6), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-2-methyquinoline (7), and 8-(4′-O-methyl-α-ribopyranosyloxy)-2-methylquinoline (8) were isolated from Actinomadura sp. BCC27169. The chemical structures of these compounds were determined based on NMR and high-resolution mass spectroscopy. The absolute configurations of these monosaccharides were revealed by the hydrolysis of compounds 7 and 8. Compounds 3 and 8 exhibited antitubercular activity at MIC 50 μg/mL. Only compound 3 showed cytotoxicity against KB cell at IC₅₀ 18.63 μg/mL, while other isolated compounds were inactive at tested maximum concentration (50 μg/mL).     

A new triterpene glycoside from sea cucumber Holothuria leucospilota

A new triterpene glycoside, leucospilotaside A, along with a known saponin, isolated from sea cucumber Holothuria leucospilota, and its structure was elucidated as 3β-O-[4-O-sodiumsulfate-β-D-quinovopyranosyl-(1→2)-β-D-xylopyranosyl]-holosta-22-ketone-9-en-17α,25α-diol (1) by extensive spectroscopic analysis and chemical methods. Leucospilotaside A (1) has a ketone carbonyl group (22) in the aglycon side chain.     

Structure determination and quantification of a new flavone glycoside with anti-acetylcholinesterase activity from the herbs of Elsholtzia ciliata

Three acacetin triglycosides (compounds 1, 2 and 3) were isolated from the herbs of Elsholtzia ciliata (Labiatae). The structure were identified as 7-O-β-D-glucopyranosyl-(1 → 2)[α-L-rhamnopyranosyl-(1 → 6)]-β-D-glucopyranoside (compound 1), 7-O-(6-O-acetyl)-β-D-glucopyranosyl-(1 → 2)[α-L-rhamnopyranosyl-(1 → 6)]-β-D-glucopyranoside (compound 2) and 7-O-(6-O-acetyl)-β-D-glucopyranosyl-(1 → 2)[(4-O-acetyl)-α-L-rhamnopyranosyl-(1 → 6)]-β-D-glucopyranoside (compound 3) of acacetin. The structures of these compounds were determined on the basis of 2D-NMR spectroscopic data. Compound 3 has not been isolated from a natural source. In addition, the three compounds were quantitatively analysed by HPLC. Acetylcholinesterase (AChE) inhibition activity was assayed to find anti-Alzheimer’s activity, since this enzyme increases the concentration of acetylcholine (ACh), a neurotransmitter, responsible for brain’s memory. Acacetin, the aglycone of the three compounds, exhibited a potent anti-cholinesterase activity (IC₅₀, 50.33 ± 0.87), though its glycosides (1, 2 and 3) were less active. HPLC analysis demonstrated that the three compounds were contained in the MeOH extract in the order of compounds 2 (12.63 mg/g extract) > 3 (3.10 mg/g) > 1 (2.92 mg/g).     

Carbazole-modified blue light-emitting copolymers with the backbones integrated by diphenyloxadiazole,fluorene, and triphenylamine

Two new blue light-emitting polymers, poly{[2,5-bis(4-phenylene)-1,3,4-oxadiazole]-[9,9-dihexylfluorene-2,7-diyl]-[N-(4-(9H-carbazol-9-yl)phenyl)-N,N-bis(p-phenylene)aniline]} (POFPA) and poly{[2,5-bis(4-phenylene)-1,3,4-oxadiazole]-[9,9-dihexylfluorene-2,7-diyl]-[4-(3,6-(di-9H-carbazol-9-yl)-9H-carbazol-9-yl)-N,N-bis(p-phenylene)-aniline]} (POFCPA), were synthesized by Suzuki coupling reactions. By GPC analysis against a linear polystyrene standard POFPA and POFCPA were found to have M_n of 1.68 × 10⁴ and 3.70 × 10³, respectively. In contrast to POFPA, the main absorption peak of POFCPA in dilute toluene solution was blue-shifted by Δλ = 26 nm owing to its backbone of relatively shorter π-conjugation length and more carbazole units in side chain. The absolute fluorescence quantum yield (Φ_f) of POFCPA in dilute toluene solution was determined as 73%, much higher than that of POFPA (Φ_f ≈ 58.9%) measured under the same conditions. An electroluminescence device based on POFCPA displays a stable blue emission having color coordinates of (0.15, 0.20), a maximum brightness of 4762 cd/m², and a maximum current efficiency of 1.79 cd/A. By using this polymer as the host material doped with 1 wt.% 4,4′-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl, the achieved highest brightness, maximum current efficiency and maximum power efficiency are 13,613 cd/m², 3.38 cd/A, and1.84 lm/W, respectively.     

A new acylated flavonoid tetraglycoside with anti-inflammatory activity from Tipuana tipu leaves

A new acylated kaempferol glycoside, kaempferol 3-O-α-l-rhamnopyranosyl-(1 → 6)-O-[β-d-glucopyranosyl-(1 → 2)-4-O-acetyl-α-l-rhamnopyranosyl-(1 → 2)]-β-d-galactopyranoside, has been isolated from the leaves of Tipuana tipu (Benth.) Lillo growing in Egypt, along with three known flavonol glycosides, kaempferol 3-O-rutinoside, quercetin 3-O-rutinoside (rutin) and kaempferol 3-O-[α-l-rhamnopyranosyl-(1 → 6)]-[α-l-rhamnopyranosyl-(1 → 2]-β-d-glucopyranoside. Structure elucidation was achieved through different spectroscopic methods. Structure relationship with anti-inflammatory activity using carrageenin-induced rat paw oedema model is discussed.     

Cavity ring-down observation of Yb3+ optical absorption in room temperature solution

Cavity ring-down spectroscopy is used to probe the optical absorption of the optical pseudo-two level system [Xe]4f¹³ Yb³⁺ in room temperature solution, a situation where the two-color pump-probe luminescence approach commonly used to study the other [Xe]4fⁿ (2 ≤ n ≤ 12) trivalent lanthanide ions fails. A 1 m optical cavity constructed from two highly reflective mirrors is used to obtain ring-down signals as a function of wavelength from 1 mL samples contained in a quartz cuvette placed in the center of the cavity. Absorption spectra constructed from these signals characteristic of the ⁶H_15/2 → ⁴F_9/2 [Xe]4f⁵ Dy³⁺ and the ⁷F₀ → ⁵D₀ [Xe]4f⁶ Eu³⁺ transitions are presented and compared to the corresponding single pass absorption and two-color pump-probe luminescence spectra to obtain sensitivity estimates. Finally the spectrum for the ²F_5/2 → ²F_7/2 [Xe]4f¹³ Yb³⁺ transition for a model Yb³⁺ complex in room temperature solution is obtained using cavity ring-down spectroscopy for the first time.     

AMoO4 (A = Mg,Ni) molybdates: Phase stabilities,electronic structures and chemical bonding properties from first principles

Stability of different phases of AMoO₄ (A = Mg, Ni) molybdates versus A–O bonding and the corresponding electronic structures are examined from first principles. The energy-volume equations of state for three forms (β, α, ω), characterized by decreasing volumes in the sequence of Mg and Ni molybdates are established. While NiMoO₄ is energy stabilized in the sequence β → α → ω, an opposite behavior is identified for the Mg molybdate. Charge analysis characterizing ionic Mg²⁺ versus covalent Ni^+1.2 behaviors can explain the trend. Electronic band structure also shows large differences: MgMoO₄ is insulating with a ～2 eV band gap while in a magnetic state, NiMoO₄ is a small gap (～0.2 eV) semi-conductor. Chemical bonding properties show weak Mg and strong Ni bonding with oxygen, while identifying the Mo–O interaction as prevailing.     

Studies on the Solution Conformation and Dynamics of the Trisaccharide Repeating Unit of the Kps from Sinorhizobium Fredii Svq293

ABSTRACT

The conformational behaviour of the major trisaccharide repeating unit (α-D-Galp-(1→2)-β-D-Ribf-(1→9)-α-5-O-Me-Kdnp-) of the polysaccharide from Sinorhizobium fredii SVQ293, a mutant derivative has been analysed by NMR spectroscopy and extensive molecular dynamics simulations. The results obtained indicate that the five-membered ring adopts an almost unique conformation as do the pyranose rings. The Ribf-(1→9)-α-5-O-Me-Kdnp linkage may adopt a variety of conformations while the α-D-Galp-(1→2)-β-D-Ribf- also populates an extended surface of the Φ/Ψ map. Two 10 ns MD simulations using the GB/SA continuum solvent model for water and the MM3* force field provides a population distribution of conformers which satisfactorily agrees with the experimental NMR data for both the glycosidic linkages and the hydroxymethyl groups.